Hydraulic conductivity of filter cake modified by autoclaved aerated concrete powder and its mechanism

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4. Hydraulic conductivity of filter cake modified by autoclaved aerated concrete powder and its mechanism

Autoclaved aerated concrete powder (AACP), a kind of solid construction waste, is produced in huge quantities. However, the utilization of AACP is still limited due to its high porosity and low compressive strength. In this work, the chemical composition of AACP was obtained based on XRF analysis. Different amounts of AACP were used to modify the filter cake obtained from Shenzhen City for application in geotechnical projects. Permeability test and Atterberg limits test were carried out to investigate the engineering properties of the untreated and AACP-treated soil samples. The mechanism of improvement in engineering properties of AACP stabilized soil was also investigated. Test results showed that the hydraulic conductivity of the sample increased significantly after AACP treatment. The hydraulic conductivity of the compacted AACP/filter cake mixture containing 60% AACP (cured for 28 days) was 34.3 times higher than that of the compacted pure soil. The formation of aggregated soil particles and the increase in void ratio were the main causes of this phenomenon. AACP consists mainly of sand particles and has a strong water absorption ability. With the addition of AACP, the liquid limit and the plastic limit of the sample increased while the plasticity index decreased. The negative correlation between the hydraulic conductivity and the plasticity index suggested that the plasticity index could be used to estimate the hydraulic conductivity. The above results improve the reuse efficiency of AACP and propose a material for the modification of soft soils.

9th International Congress on Environmental Geotechnics (ICEG2023)

Advances in Testing and Material Characterization